Over the past 10 years, the incidence of thyroid cancer in women has been increasing faster than any other cancer in either women or men. Yet its causes are still largely unknown, although several promising avenues related to nutrition have emerged. The proposed study will use previously collected, prospective data to verify and expand on these findings. In addition, we will address an emerging hypothesis regarding the impact of insulin on thyroid cancer risk. Our specific aims are: (1) to evaluate the relationship between papillary thyroid cancer risk and (a) cruciferous vegetables and isothiocyanates, using a newly developed database, and (b) overall and abdominal adiposity; and (2) to evaluate the association between papillary thyroid cancer risk and dietary factors that are (a) positively related to insulin levels (i.e., refined grains and glycemic load) and (b) inversely related to insulin levels (i.e., whole grains and fiber). These analyses will take place in the context of the California Teachers Study (CTS) and include 117,646 women. Over a ten- year follow-up period (through December 31, 2005), it is anticipated that 154 cases of papillary thyroid cancer will be diagnosed within this cohort. Cancer cases are identified through annual linkage with the California Cancer Registry (CCR) and are over 99% complete. Cohort follow-up for vital status and continued California residence is accomplished through contact with participants and linkage with various databases. Usual dietary intake was assessed at baseline using a validated food-frequency questionnaire. Height and weight were self-reported at baseline and waist and hip circumferences self-measured at the first follow-up; these measurements have also been validated against interviewer measurements in a subsample of the cohort. Cox proportional hazards models with age as the time scale and adjusting for birth cohort will be used to calculate relative risks. The results of this research will have important implications for improving our understanding of the etiology of this disease which disproportionately affects young women. [unreadable] [unreadable] [unreadable]